Non-contact pressure switch assembly

Abstract

A non-contact pressure switch assembly for sensing pressure in, e.g., a vehicle. A piston with integrated magnet in a housing is moved under fluid pressure to change a magnetic field in which a Hall sensor is disposed inside the housing. The field changes polarity at the Hall sensor at a predetermined piston position.

1 . A pressure switch assembly, comprising:
 a housing disposable in a fluid;   an opening in the housing, the opening being in fluid communication with the fluid when the housing is disposed therein;   a piston disposed adjacent the opening for reciprocal movement in the housing;   at least one magnet coupled to the piston for movement therewith;   at least one Hall effect sensor in the housing and outputting a signal that is affected by the position of the magnet in the housing; and   a spring urging the piston toward the opening, fluid pressure urging the piston away from the opening.   
   
   
       2 . The pressure switch assembly of  claim 1 , wherein the Hall effect sensor establishes at least in part a Hall switch changing output state from negative to positive at a predetermined position of the magnet in the housing. 
   
   
       3 . The pressure switch assembly of  claim 2 , wherein the spring and motion of travel of the piston together establish a pressure switch value. 
   
   
       4 . The pressure switch assembly of  claim 2 , wherein the magnetic field of the magnet switches polarity relative to the Hall switch at a predetermined position of the magnet relative to the Hall switch. 
   
   
       5 . The pressure switch assembly of  claim 1 , wherein the housing includes a bottom and a base plate flush against the body and defining the opening, a diaphragm being disposed between the body and base plate. 
   
   
       6 . A method for sensing pressure, comprising moving a piston under fluid pressure to change a magnetic field in which a Hall sensor is disposed, the field changing polarity at the Hall sensor at a predetermined piston position. 
   
   
       7 . The method of  claim 6 , wherein the piston is in a housing having an opening, and the housing is disposed in the fluid such that the opening is in fluid communication with the fluid. 
   
   
       8 . The method of  claim 7 , comprising coupling the piston to at least one magnet, wherein the Hall sensor outputs a signal that is affected by the position of the magnet in the housing and hence represents pressure. 
   
   
       9 . The method of  claim 8 , comprising disposing a spring in the housing such that the spring urges the piston toward the opening, with fluid pressure urging the piston away from the opening. 
   
   
       10 . The method of  claim 7 , wherein the Hall sensor establishes at least in part a Hall switch changing output state from negative to positive at a predetermined position of the magnet in the housing. 
   
   
       11 . The method of  claim 9 , wherein the spring and motion of travel of the piston together establish a pressure switch value. 
   
   
       12 . The method of  claim 8 , wherein the magnetic field of the magnet switches polarity relative to the Hall sensor at a predetermined position of the magnet relative to the Hall sensor. 
   
   
       13 . The method of  claim 7 , wherein the housing includes a bottom and a base plate flush against the body and defining the opening, a diaphragm being disposed between the body and base plate. 
   
   
       14 . A non-contact pressure switch assembly for sensing pressure in a vehicle, comprising:
 at least one housing;   at least one Hall sensor associated with the housing;   at least one piston with integrated magnet the housing, the piston with magnet being moved under fluid pressure to change a magnetic field in which the Hall sensor is disposed, wherein the field changes polarity at the Hall sensor at a predetermined piston position.   
   
   
       15 . The pressure switch assembly of  claim 14 , wherein an opening is in the housing and the opening is in fluid communication with fluid when the housing is disposed therein, the piston being disposed adjacent the opening for reciprocal movement in the housing. 
   
   
       16 . The pressure switch assembly of  claim 15 , comprising a spring urging the piston toward the opening, fluid pressure urging the piston away from the opening. 
   
   
       17 . The pressure switch assembly of  claim 14 , wherein the Hall effect sensor establishes at least in part a Hall switch changing output state from negative to positive at a predetermined position of the magnet in the housing. 
   
   
       18 . The pressure switch assembly of  claim 16 , wherein the spring and motion of travel of the piston together establish a pressure switch value. 
   
   
       19 . The pressure switch assembly of  claim 14 , wherein the magnetic field of the magnet switches polarity relative to the Hall sensor at a predetermined position of the magnet relative to the Hall sensor. 
   
   
       20 . The pressure switch assembly of  claim 15 , wherein the housing includes a bottom and a base plate flush against the body and defining the opening, a diaphragm being disposed between the body and base plate.